Regulator for dynamos



(No Model.) 3 Sheets-Sheet 1.

J. J..WOOD.

REGULATOR FOR DYNAMOS. No. 426,699. Patented Apru29, 1890.

INVENTOR: WITNESSES: 2 9; M

(No Model.) 3 Sheets-Sheet 2.

J. J. WOOD.

REGULATOR FOR DYNAMOS.

No. 426,699. Patented Apr. 29, 1890.

FIG. 2.

INVENTOR:

WITNESSES (3W 9; z ea By his Attorneys, fiw Wm u (No Model.) A sSheets-Sheet 3. J. J. WOOD.

REGULATOR FOR DYNAMOS.

No. 426,699. Patented Apr. 29, 1890.

FIG. 4.

. INVENTOR: WITNESSES: ward 93? By 112's Altai e 15,

m.dnwn G UNITED STATES PATENT OFFICE.

JAMES J. IVOOD, OF BROOKLYN, NEiV YORK.

REG U LATOR FOR DYNAMOS.

SPECIFICATION forming part of Letters Patent No. 426,699, dated April29, 1890.

Application filed August 20, 1889. Serial No. 821,843. (No model.)

To all whom. it may concern:

Be it known that I, JAMES J'. WVOOD, a citizen of the United States,residing at Brooklyn, in the county of Kings and State of New York, haveinvented certain new and useful Improvements in Regulators for Dynamo-Electric Machines, of which the following is a specification.

This invention relates to current-regulators for dynamo-electricmachines of that class which maintains a constant current upona circuitof varying resistance. Dynamos feeding arc lamps or electromotors inseries are of this class. WVith the regulation of such dynamcs it isessential to vary the electromotive force generated in proportion to thevariations of resistance on the circuit, in order that when theresistance increases, and the current consequently is reduced, theelectromotive force shall be increased sufficiently to restore thecurrent to its normal volume, and, conversely, when the resistancedecreases, and the current consequentlyis augmented, to proportionatelydiminish the electro-motive force generated, and thereby reduce thecurrent to the normal. My invention provides a new means foraccomplishing this result. In addition to the usual maincommutator-brushes I provide a pair of auxiliary brushes which areplaced on opposite sides of one of the main brushes, so as to makecontact with segments of like and equal potential, so that no currentflows through a bridge connecting the brushes. These brushes areconnected by a shunt-circuit either with the opposite main brush or witha similar pair of auxiliary brushes, so that a current flows throughthis shunt. I11 this shunt is placed a variable rheostat, which isoperated by a regulating-magnet included in the main circuit and themoving member of which is connected to the rheostat in such manner as tovary its resistance in an inverse proportion to the excitation of themagnet. Thus as the line-current increases the magnet becomes moreexcited, the resistance of the rheostatis reduced, and a leakage orescape of current is permitted through the shunt-circuit across from oneside of the commutator to the other, whereby the difference ofpotentials at the main brushes is reduced, which results in a reductionof the electromotive force in the main circuit.

Figure 1 of the accompanying drawings is a diagrammatic view of a dynamoand circuit to which my invention in its preferred form is applied. Fig.2 is a diagrammatic elevation of the commutator, illustrating the positions of the respective brushes. Fig. 3 is a view similar to Fig. l,butillustrating a modification.

Let A designate the armature of the dynamo, F F the field-magnetthereof, C the commutator, B B .the main commutatorbrushes, and D D thefield-exciting coils. The main brushes B B and coils D D are connected,as usual, in series in the main circuit or line a a, in which areintercalated in series are lamps L L or electromotors or other so-calledtranslating devices. A regulating-magnet M has its coils also connectedserially in the line-circuit. This magnet may be of the ordinarytype,but is preferably of the solenoid type, as shown. The maincommutatorbrushes B B are placed to touch the commu tator on the neutralline as :r, as usualthat is, in the position of maximum difference ofpotentials, and consequently of maximum current.

In addition to the main brushes there are applied to the commutator twoauxiliary brushes 1) I), which are arranged to bear upon the commutatoron opposite sides of the neutral line and at points equally distanttherefrom, so that they touch segments the potentials of which areequal. If the curve of potentials of the commutator is abnormal ordistorted, it will be necessary to place one of these brushes fartheraway from the neutral line than the other, in order that segmentstouched by both shall be of like and equal potential. The two auxiliarybrushes 1) b are connected by a conducting bridge or circuit 0, and thisbridge forms part of a shunt-circuit d d, which extends thence through arheostat or variable resistance R to. one of the main brushes B. It isshown in Fig. 1 asv extending to the lower or positive brush B; but itmight extend instead to the upper or negative brush without changing theoperation. e have thus a shunt-circuit of variable resistance interposedbetween the auxiliary brushes Z) Z) and the main brush 13+.

The rheostat R, which may be of any suitable construetiomis connected tothe regulat- IOO ing-magnet Min such manner that as the excitation ofthe magnet increases the resistance of the rheostatis decreased. In Fig.1 the rheostat is shown as consisting of a glass or earthenware jar e,filled with liquid, which may be acidulated water, and in which are twocarbon plates f g, the former lying on the bottom of the jar and thelatter being suspended above it through the medium of a stem g,depending from one arm of a lever h, the other arm of which is connectedthrough a rod 2' with the moving member of the regulating magnet M. Thismagnet is provided with a dash-pot P to check sudden or excessivemovements. The carbon plates f g are connected, respectively, withopposite wires of the shuntcircuit d d, as clearly shown. By reason oftheir separation the resistance of the intervening mass of liquid isinterposed in the shunt-circuit. As the excitation of the magnet Mincreases the plate g is lowered or caused to approach the plate f, sothat the intervening column of liquid is of less height, andconsequently of less resistance. As the excitation of the magnetdecreases the plate g rises, therebyincreasing the resistance. Duringthe normal running .of the dynamo the resistance of the rheostat is sogreat that but Very little current flows through the shunt (Z d. Incase, however, the resistance of the circuit a a is reduced by theswitching out of one or more lamps L L the consequent augmentation ofthe current excites the magnet M to above the normal and causes it toreduce the resistance of the rheostat R. Thereupon an increased currentflows through the shunt cl cl, thereby to the extent of the reduction ofthe resistance in this shunt shortcircuiting the armature-coilscorresponding to the portion of the commutator intervening between thebrushes Z) I) and the brush 13+. It results from this short-circuitingthat the diiference of potentials between the positive and negative mainbrushes is reduced, so that the electro-motive force of the line-currentis diminished, and consequently the current falls until by its effectupon the magnet M the resistance of the rheostatR is increased to suchan extent that an equilibrium is attained, whereby the current on theline is restored to the normal volume. result follows an increase ofresistance on the line, the current being first diminished, resulting inan increase of resistance in the rheostat, a decreased short-circuit orleakage through the shunt cl cl, and a consequent i11- crease in theelectro-motive force developed until the current is restored to thenormal.

The position of the auxiliary brushes 1) Z) may be greatly varied. Inthe diagram, Fig. 2, they are shown as touching the commutator onsegments intersected by an imaginary line 1), crossing the commutatorperpendicularly to the neutral line a: 00. A number'of other lines o '0are drawn across the commutator parallel with this line 1). All of theselines are drawn across between commutatoi se The contrary proposed.

ments of equal and like potentials. It the curve of potentials of thecommutator be distorted, these lines o Q: will be more or less deflectedfrom true perpendicularity to the neutral line ac as.

The auxiliary brushes 1) b may be arranged to touch the respectivesegments intersected by any of the lines '0 othat is to say, they may beplaced at any part of the commutator, provided that they be on oppositesides of the neutral line and be arranged in positions of equal and likepotentials. For example, if one of these brushes be placed on the leftside of the neutral line in a position where it develops relatively tothe negative main brush a positive potential of, say, one hundred andtwenty-six volts, then the other brush b must be placed on theright-hand side of the neutral line and in such position that it alsoshall develop a positive potential of one hundred and twenty-six volts.

The two auxiliary brushes may be placed very close to one of the mainbrushes or midway between the main brushes, or close to the oppositemain brush, or in any intermediate position. For example, they may beplaced in the positions shown in dotted lines at b b in Fig. 2, wherethey touch the commutator on the line 12 The nearer the auxiliarybrushes are placed to the main brush which constitutes the oppositeterminal of the sh untcircuit (Z the less will be the resistance of therheostat R, and vice versa. Thus with a rheostat of given resistance itis easy to adjust the brushes 6 1) until they develop such a potentialrelatively to the main brush B with which the opposite terminal of theshunt connects as to secure the proper proportions of resistance topotential for attaining the best results by this system of regulation.

Fig. 3 shows a different form of rheostat R, consisting of a series ofresistance-coils 9' r, terminating in contact-springs s s, which aretouched by the lever h as it is vibrated by the magnet M. hen the magnetM is relaxed, the lever h is drawn up by the weight of the armature orby a spring j, so that it touches only the terminal contact-spring s, orit may even break contact with this, thereby breaking the shunt-circuit(Z, and as the magnet M is excited the lever h is vibrated, so that itmakes contact successively with the springs s s. In the former positionall the coils r r are in series and the resistance in the shunt is atits maximum, while when the magnet M is fully excited all the coils r rare cut out and the resistance is reduced to the minimum. This form ofrheostat is well known.

In Fig. 3 the terminals of the shunt-circuit d are shown as bothconnected to the respective main brushes B B, as has been heretoforeThis arrangement is inferior to the arrangement of the shunt between theauxiliary brushes and one of the main brushes, as introduced by myinvention, for the reason that a very much higher resistance is requiredin the shunt-circuit, and also because of the inability to vary theelectro-motive force in the shunt to adapt it to a rheostat of givenresistance.

My improvement is characterized by shortcircuiting through the shunt donlyaportion of the armature, in contradistinction to shortcircuitingthe entire armature, as by the con nection shown in Fig. 3. The formerresult may be accomplished by the use of two sets of auxiliary brushes,one end of the shunt being connected to the brushes 1? b in Fig. 2 andthe other end to brushes set in other p0- sitions-as, for example, at bb. This arrangement is shown in Fig. 4. In this case only the portion ofthe armature corresponding to the commutator-segments interveningbetween these two sets of brushes will be short-circuited through theshunt.

My invention provides a simple, cheap, and easily applied and adjustedmeans of regulation which is well adapted to small dynamos and may bemade advantageously applicable to large machines of high voltage.

I claim as my invention the following-defined novel features orcombination, substantially as hereinbeiore specified, namely:

1. The combination, with a dynamo-electric machine, of a regulatortherefor, consisting of two auxiliary brushes applied to opposite sidesof the commutator in positions of like and equal potentials, aconducting-bridge connecting said brushes, a shunt from said brushes toa brush or brushes in contact with commutator-segments of opposite ordiiferent potential, and a variable rheostat in said shunt.

2. The combination, with a dynamo-electric machine, of a regulatortherefor, consisting of two auxiliary brushes applied to opposite sidesof the commutator in positions of like and equal potentials, aconducting-bridge connecting said brushes, a shunt from said brushes toone of the main brushes, and a variable rheostat in said shunt.

In witness whereof I have hereunto signed my name in the presence of twosubscribing witnesses.

JAMES J. WOQD.

